We report a seeded optical parametric generator (OPG) producing tunable radiation from 4.2-4.6 ?m. The seeded OPG employs a 13 mm long CdSiP2 (CSP) crystal cut for non-critical phase-matching, pumped by a nanosecond-pulsed, MHz repetition rate Raman fiber amplifier system at 1.24 ?m. A filtered, continuous-wave fiber supercontinuum source at 1.72 ?m is used as the seed. The source generates up to 0.25 W of mid-infrared (MIR) idler power with a total pump conversion of 42% (combined signal and idler).In recent years, multi-petawatt laser installations have achieved unprecedented peak powers, opening new horizons to laser-matter interaction studies. Ultra-broadband and extreme temporal contrast pulse requirements make optical parametric chirped pulse amplification (OPCPA) in the few-picosecond regime the key technology in these systems. To guarantee high fidelity output, however, OPCPA requires excellent synchronization between pump and signal pulses. Here, we propose a new highly versatile architecture for the generation of optically synchronized pump-signal pairs based on the Kerr shutter effect. We obtained &gt;550?J pump pulses of 12 ps duration at 532 nm optically synchronized with a typical ultrashort CPA source at 800 nm. As a proof-of-principle demonstration, our system was also used for amplification of ?20?J ultra-broadband pulses based on an OPCPA setup.The use of Eu3+ codoping for enhancing the Ho3+5I5→5I6 emission in fluoroindate glasses shows that Eu3+ could depopulate the lower laser state Ho3+5I6 while having little effect on the upper state Ho3+5I5, resulting in greater population inversion. https://www.selleckchem.com/products/lithium-chloride.html The Ho3+/Eu3+ codoped glass has high spontaneous transition probability (6.31s-1) together with large emission cross section (7.68×10-21cm2). This study indicates that codoping of Ho3+ with Eu3+ is a feasible alternative to quench the lower energy level of the 3.9 ?m emission and the Ho3+/Eu3+ codoped fluoroindate glass is a promising material for efficient 3.9 ?m fiber lasers.Silicate-clad heavily Yb3+ doped phosphate core multimaterial fiber (MF) was successfully drawn by using a molten core method, which has a high gain per unit length of 5.44 dB/cm at 1.06 ?m. What is more, an all-fiber-integrated passively mode-locked fiber laser based on a 5 cm long MF was built. The mode-locked pulses operate at 1055 nm with a period of ?555ps, and the fundamental repetition rate is 1.787 GHz. For the first time, to the best of our knowledge, we demonstrate the realization of a mode-locked fiber laser with a gigahertz fundamental repetition rate based on a silicate-clad heavily Yb3+ doped phosphate core MF.We propose a lensfree on-chip microscopy approach for wide-field quantitative phase imaging (QPI) based on wavelength scanning. Unlike previous methods, we found that a relatively large-range wavelength diversity not only provides information to overcome spatial aliasing of the image sensor but also creates sufficient diffraction variations that can be used to achieve motion-free, pixel-super-resolved phase recovery. Based on an iterative phase retrieval and pixel-super-resolution technique, the proposed wavelength-scanning approach uses only eight undersampled holograms to achieve a half-pitch lateral resolution of 691 nm across a large field-of-view of 29.85mm2, surpassing 2.41 times the theoretical Nyquist-Shannon sampling resolution limit imposed by the pixel size of the sensor (1.67 ?m). We confirmed the effectiveness of this technique in QPI and resolution enhancement by measuring the benchmark quantitative phase microscopy target. We also showed that this method can track HeLa cell growth within an incubator, revealing cellular morphologies and subcellular dynamics of a large cell population over an extended period of time.Dissipative Kerr solitons in ultra-high-Q resonators are extremely sensitive to the thermal behavior of the resonators. Especially for resonators with hydrophilic surfaces, moisture continuously adsorbs on their surfaces and causes additional absorption loss that results in an excessive thermal shift of resonance frequency. This change makes soliton mode locking more challenging or even impossible. Here, we report hydrophobic monolayer passivation using hexamethyldisilazane on ultra-high-Q silica wedge resonators. It was experimentally confirmed that the Q-factor and dispersion were maintained after passivation, and excess thermal shift by moisture was inhibited for more than three days in the atmosphere. Soliton mode locking was successfully performed with the resonator one month after passivation.A novel, to the best of our knowledge, and simple heterodyne interferometer that uses spatially separated input beams to minimize the influence of the periodic nonlinearity is constructed. A custom designed polarizing beam displacer is used to split the input beams to parallel outputs with orthogonal polarizations, which provides a balanced path and completely symmetric structure for the interferometer. This novel optical setup suppresses the nonlinearity caused by the frequency and polarization mixing, and the very simple optical structure makes the interferometer less susceptible to environmental turbulence with potential use in many sensor applications. Experiments have confirmed that the interferometer maintains sub-nanometer nonlinearities in the laboratory environment.We propose an off-axis deflectometric microscope system for microscopic surface testing with both high measurement accuracy and a large slope dynamic range. A high-luminance liquid crystal display directly illuminates the tested sample with coded fringes, and then the reflected fringes passing through a microscope objective are captured by a pinhole camera, from which the deflectometric microscopic testing with a large slope range can be achieved. The accuracy of the proposed system is validated numerically and experimentally, and a large measurable slope dynamic range is also demonstrated. The proposed system provides a feasible way with the slope range in the order of sub-radians and sag resolution better than 0.05 nm.High-harmonic spectra in solids driven by linearly polarized laser pulses contain diverse polarization dependence and fine modulation in the harmonic yields. In this work, we attribute the direction-dependent features of harmonic yields to the collective roles of tunneling rate, quantum-path interference, and joint density of state (JDOS). In addition, we distinguish the dominant contribution between quantum-path interference and the Van Hove singularity of JDOS, and demonstrate that the emergence of spectral enhancement in the vicinity of cutoff frequency is determined by the Van Hove singularity of JDOS. Polarization-resolved high-harmonic spectra are a promising spectroscopic tool to probe the electronic structure and dynamics in solids and thus open a door to measure Van Hove singularities and the energy band with high-resolution crystal momentum.